The thermal stability of high burning rate propellant is studied by DSC, methyl violet test and weight loss test. With the help of thermal accelerated aging test, the curves of change of the effective stabilizer with time during the thermal decomposition of propellants at 65 ℃,75 ℃,85 ℃and 95 ℃ are obtained. In the calculation of life, the time (τ) needed for consuming the effection. stabilizer of 50% at various temperatures (T) is defined as the end point of safe storage life of the propellant. The values of τ at various temperatures are fitted to Bethelot's equation, T=a+blogτ, by the linear least-squares method. With the help of the obtained equations, the safe storage life at 30 ℃ is predicted for four high burning rate propellants. The results show that the relative thermal stability of the propellant containing 1,3-dimethyl-1,3-diphenyl urea (C2) and CdO (A), the propellant containing resorcin (ReS), C2 and CdO (B) and the propellant containing C2 and Res (C) decreases in the order A>B>C. Replacing Res partly or wholly with CdO as a stabilizer increases the thermal stability and extends the storage life of propellants. The storage in closed environment is an effective way for improving the stability and extending the storage life of the propellant containing ReS.